\begin{table}[htbp]\centering
\caption{Robust IV Estimates of Log Registrations per Capita on Log Highway Gas Use per Capita \label{tab:GasUsePerCapitaiv}}
\begin{tabular}{l*{4}{c}}
\hline \hline \multicolumn{5}{l}{\textit{Panel A: IV Estimates and Robust 95\% Confidence Intervals}} \\&            &            &            &            \\
\multicolumn{5}{c}{Dep. Var.: Log Number of Vehicle Registrations} \\ &         (1)&         (2)&         (3)&         (4)\\
$\gamma$    &      -0.353&       -0.34&       -0.62&       -0.85\\
95\% Conf. Set&[-0.95, 0.07]&[-0.95, 0.07]&[-6.45, 0.06]&\makecell{(-$\infty$, $0.16]$; \nextline $[3.09$, $\infty$)}\\
\makecell[l]{Data Source \nextline Controls}&        None&  Documented&\makecell{Large \nextline Undocumented}&\makecell{Small \nextline Undocumented}\\
State Fixed Effects&           Y&           Y&           Y&           Y\\
Year Fixed Effects&           Y&           Y&           Y&           Y\\
\makecell[l]{State-Specific Linear \\ Time Trends}&           Y&           Y&           Y&           Y\\
Common Controls&           Y&           Y&           Y&           Y\\
Number of Obs.&       2,429&       2,429&       2,429&       2,429\\
\hline \hline \multicolumn{5}{l}{\textit{Panel B: Anderson-Robin Test Statistics and P-Values}} \\&            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=11$}} \\ AR Stat&   11.515***&   11.233***&     5.450**&      2.732*\\
p-value     &       0.001&       0.001&       0.020&       0.098\\
            &            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=9.7$}} \\ AR Stat&   11.549***&   11.269***&     5.529**&      2.790*\\
p-value     &       0.001&       0.001&       0.019&       0.095\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$1}} \\ AR Stat&   11.066***&   11.050***&    8.745***&     5.808**\\
p-value     &       0.001&       0.001&       0.003&       0.016\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-4.8}} \\ AR Stat&   10.179***&    9.899***&      3.506*&       1.439\\
p-value     &       0.001&       0.002&       0.061&       0.230\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-6.1}} \\ AR Stat&   10.437***&   10.150***&      3.785*&       1.608\\
p-value     &       0.001&       0.001&       0.052&       0.205\\
\hline \hline \end{tabular} \vspace{0.2cm} \begin{tablenotes} \begin{spacing}{0} \begin{footnotesize} \item \textbf{Notes:} The top panel of this table presents IV estimates and 95\% confidence sets robust to weak instruments of the linear relationship between log highway gas use per capita and log vehicle registrations per capita.  The bottom panel presents Anderson-Rubin chi-squared statistics along with p-values for different null hypotheses pertaining to the parameter estimated in the top panel.  The unit of observation is state-year.  The four specifications pertaining to different levels of  (DSCs) and control specifications are documented in Table \cref{ssec:Spec}. Confidence sets are based on standard errors clustered by state. * p\textless 0.1, ** p\textless 0.05, *** p\textless 0.01 \end{footnotesize} \end{spacing} \end{tablenotes} \end{table}
